ᐅ Energy Saving Regulation 2016 / KFW55 Standard / Gas and Solar in 2016
Created on: 1 Dec 2015 20:37
G
Grym
I have a question regarding the 2016 energy saving regulation. It is often stated that the transmission heat loss is reduced by 20 percent, but I cannot find this figure, unlike the change in primary energy demand, in the legal text. Instead, it says:
Does this actually mean that these reference values have not applied before and only became valid from January 2016? Is the 20-percent tightening only implicit or calculated?
Furthermore, the KFW55 standard is based on these reference values concerning transmission heat loss. KFW55 corresponds to 70 percent, so is KFW55 about 30 percent stricter than the 2016 energy saving regulation regarding this parameter?
This is also suggested by the simplified benchmark values for KFW55, e.g., thermal bridge allowance 0.05 x 0.7 = 0.035 or 0.28 x 0.7 = 0.2. “Simplified” is relative, as you still have to calculate all thermal bridges.
Then the equation that KFW70 is roughly equivalent to the 2016 energy saving regulation is definitely not correct. KFW70 is at 85 percent of the reference values, while the 2016 energy saving regulation refers to 100 percent of the reference values. Therefore, KFW70 is still 15 percent stricter regarding transmission heat loss than the new energy saving regulation. Only in comparison of primary energy are the values closer, where KFW70 demands 70 percent and the energy saving regulation a tightening by 25 percent, so 75 percent.
This brings us to gas plus solar in 2016. A KFW70 house exceeds both primary energy demand and transmission heat loss requirements of the 2016 energy saving regulation. If there were KFW70 houses with gas plus solar before, there will continue to be. The requirements of the Renewable Energies Heat Act are met by the system under point I. 1.) a) aa).
Any opinions? Corrections? Counterarguments? Theories? Other comments?
From January 1, 2016, the specific transmission heat loss related to the heat-transmitting building envelope of a new residential building must not exceed 1.0 times the corresponding value of the respective reference building.
Does this actually mean that these reference values have not applied before and only became valid from January 2016? Is the 20-percent tightening only implicit or calculated?
Furthermore, the KFW55 standard is based on these reference values concerning transmission heat loss. KFW55 corresponds to 70 percent, so is KFW55 about 30 percent stricter than the 2016 energy saving regulation regarding this parameter?
This is also suggested by the simplified benchmark values for KFW55, e.g., thermal bridge allowance 0.05 x 0.7 = 0.035 or 0.28 x 0.7 = 0.2. “Simplified” is relative, as you still have to calculate all thermal bridges.
Then the equation that KFW70 is roughly equivalent to the 2016 energy saving regulation is definitely not correct. KFW70 is at 85 percent of the reference values, while the 2016 energy saving regulation refers to 100 percent of the reference values. Therefore, KFW70 is still 15 percent stricter regarding transmission heat loss than the new energy saving regulation. Only in comparison of primary energy are the values closer, where KFW70 demands 70 percent and the energy saving regulation a tightening by 25 percent, so 75 percent.
This brings us to gas plus solar in 2016. A KFW70 house exceeds both primary energy demand and transmission heat loss requirements of the 2016 energy saving regulation. If there were KFW70 houses with gas plus solar before, there will continue to be. The requirements of the Renewable Energies Heat Act are met by the system under point I. 1.) a) aa).
Any opinions? Corrections? Counterarguments? Theories? Other comments?
Goldi09111 schrieb:
I’m not concerned about KfW 55 but whether it is even allowed to build without solar, yet with controlled ventilation with heat recovery.
Yes, you are allowed, as long as your building meets at least the Energy Saving Ordinance 100 overall in the calculation.
You must build according to this standard.
This roughly corresponds to the “old” KfW 70, although some values have been tightened, such as the transmission heat loss.
My KfW 70 building is also heated with a gas condensing boiler. Additionally, thermal solar and controlled ventilation with heat recovery are installed.
Not included: wood stove/fireplace, photovoltaics—which came later...
The house performs about 40% better than the former KfW 70 requirement, approaching KfW 55, but it will never fully reach it... (With the photovoltaics installed later: yes, but adding them afterwards doesn’t really help).
Weak points are:
Floor slab insulation
Windows overall 1.1 U-value (I could have chosen 0.8 U-value for an extra cost).
Front door: a real disaster, U 1.7, luckily it’s small...
The controlled ventilation with heat recovery already contributes significantly! If I understand the numbers correctly (and I believe I do), the controlled ventilation provides noticeably more benefit than the thermal solar system.
Whether this will be sufficient in your case can only be determined by the calculation for your individual building project.
Best regards,
Thorsten
G
Goldi0911115 May 2016 21:23Thank you for your detailed post.
I think a final calculation really needs to be done. The architect (who is likely being considered) strongly supports deep geothermal drilling and is against having three different systems (gas, solar, and controlled ventilation)... However, I can well imagine that for an architect, geothermal energy makes it much easier to meet the energy-saving regulations and that is why it is often recommended.
I think a final calculation really needs to be done. The architect (who is likely being considered) strongly supports deep geothermal drilling and is against having three different systems (gas, solar, and controlled ventilation)... However, I can well imagine that for an architect, geothermal energy makes it much easier to meet the energy-saving regulations and that is why it is often recommended.
1. You’re very welcome.
2. A colleague and friend of mine built a house in Thuringia shortly after I did, using deep geothermal drilling. It was a new system, the first from the manufacturer. COP 5.7. Truly impressive, both the house and the heating system.
3. You have to consider a) the cost of deep geothermal drilling and b) whether it’s even possible at your location. For me, b) was not an option, so a) didn’t become a painful issue.
4. In my opinion, a mechanical ventilation system with heat recovery is always a good idea. We find it fantastic for indoor climate. That it also saves some energy is a bonus. You can pretty much leave that out of the debate. It might be possible to operate a more vapor-permeable building successfully without mechanical ventilation, but I wouldn’t rely on that. Vapor-tight construction equals a greenhouse effect. You’ll end up stuck indoors like a tele-tubby. Another friend nearby didn’t install one... Steffi and I say: suffocating slowly. If you’re building today, my personal view is that a mechanical ventilation system with heat recovery should be part of the house. If you have a sufficient budget, also consider adding humidification and cooling functions.
5. Solar thermal combined with a heat pump: pure nonsense. Even an air-to-water heat pump with a COP of 3.5 (yearly) performs better in summer... So: if you don’t have a heat pump but a gas system, then solar thermal makes sense. And please use vacuum tube solar collectors, not flat plate. It’s worth the investment, you’ll be grateful. I regret only having the standard flat plates—they only work well in Tenerife-like weather...
Best regards,
Thorsten
2. A colleague and friend of mine built a house in Thuringia shortly after I did, using deep geothermal drilling. It was a new system, the first from the manufacturer. COP 5.7. Truly impressive, both the house and the heating system.
3. You have to consider a) the cost of deep geothermal drilling and b) whether it’s even possible at your location. For me, b) was not an option, so a) didn’t become a painful issue.
4. In my opinion, a mechanical ventilation system with heat recovery is always a good idea. We find it fantastic for indoor climate. That it also saves some energy is a bonus. You can pretty much leave that out of the debate. It might be possible to operate a more vapor-permeable building successfully without mechanical ventilation, but I wouldn’t rely on that. Vapor-tight construction equals a greenhouse effect. You’ll end up stuck indoors like a tele-tubby. Another friend nearby didn’t install one... Steffi and I say: suffocating slowly. If you’re building today, my personal view is that a mechanical ventilation system with heat recovery should be part of the house. If you have a sufficient budget, also consider adding humidification and cooling functions.
5. Solar thermal combined with a heat pump: pure nonsense. Even an air-to-water heat pump with a COP of 3.5 (yearly) performs better in summer... So: if you don’t have a heat pump but a gas system, then solar thermal makes sense. And please use vacuum tube solar collectors, not flat plate. It’s worth the investment, you’ll be grateful. I regret only having the standard flat plates—they only work well in Tenerife-like weather...
Best regards,
Thorsten
Goldi09111 schrieb:
I’m not concerned about KfW 55 but whether it is even allowed to build without solar panels but with controlled mechanical ventilation with heat recovery.Yes, that is definitely possible. One of the general contractors we are considering has exactly this as their standard. Since 2016, the building specifications here have replaced the traditional ventilation system with a decentralized ventilation system.
G
Goldi0911116 May 2016 00:01Thank you for the information.
I’m curious to see if this will also work for our house and our planning, as in my opinion the additional costs for solar thermal systems will never pay off (possibly more than 50 years).
I’m curious to see if this will also work for our house and our planning, as in my opinion the additional costs for solar thermal systems will never pay off (possibly more than 50 years).
Goldi09111 schrieb:
In my opinion, solar thermal will never justify the additional costs (possibly >50 years).The reality with conventional collectors is even worse. You also have to factor in the electricity costs for the circulation pump (about 40 W) as well as the financing costs.
Depending on how optimistically I calculate, it comes to over 80 years.
This is because the system works well in direct sunlight—but only then. Unfortunately, that is very rare here. Short periods of sun aren’t enough because the stratified storage tank is heated from the bottom first; often, nothing reaches the top. This does slow down heat loss somewhat, but it’s only a drop in the ocean.
In other words: with conventional collectors, the usable operating time is simply too low at this latitude.
That’s why I regret not knowing this earlier—I would have chosen the vacuum tube collector instead. It also works during transitional seasons and doesn’t require direct sunlight to start running.
Best regards,
Thorsten
Similar topics